Resinous materials, among them, transparent resinous materials, which are represented by polycarbonate or the like, have been utilized widely in various applications while taking advantages of such characteristics as being low specific gravity as well as lightweight, being processed easily, and being strong against shocks compared with inorganic glass. Recently, from such a viewpoint as saving petroleum resources or reducing carbon dioxide emissions, the momentum for upgrading mileage or fuel consumption has been enhancing by means of substituting plastics for window glasses and interior/exterior materials for automobile in order to make them lightweight.
On the contrary, resinous materials have the following disadvantages: their surface is likely to be damaged so that the gloss or transparency is likely to be lost; they are likely to be damaged by organic solvents; or moreover, they are poor in the weatherability (e.g., the photo stability against ultraviolet rays, etc.) and heat resistance; and the like. Window glasses for automobile are often exposed to sunlight for a long period of time. Consequently, in the case of using resinous materials for members for automobile, it is necessary to impart them wear resistance and weatherability by means of covering their surface by a protective film, and so forth.
As such a protective film that is good in terms of the wear resistance and weatherability, a hard coating layer is given which is made by curing a photo curing-type coating-agent composition, for instance.
As a light curing-type coating-agent composition being provided with both wear resistance and weatherability combinedly, a composition for forming wear-resistant coating has been known (see Patent Literature No. 1). The composition comprises colloidal silica fine particles, a monomer mixture, and a photo-polymerization initiator in a specific proportion, respectively. The colloidal silica fine particles include a silane compound having a methacryloyloxy group, an acryloyloxy group or a vinyl group that is modified superficially in a predetermined weight proportion. The monomer mixture includes a poly[(meth)acryloyloxyalkyl]isocyanurate, and a urethane poly(meth)acrylate, which has an alicyclic framework.
Moreover, another coating-agent composition has also been known (see Patent Literature No. 2). The coating-agent composition includes the following in a specific proportion, respectively: a poly(meth)acrylate of mono- or poly-pentaerythritol; a urethane poly(meth)acrylate, which has at least two radically-polymerizable unsaturated double bonds; a poly[(meth)acryloyloxyalkyl](iso)cyanurate; an ultraviolet absorber; a hindered amine-based light stabilizer; and a photo-polymerization initiator.
An example is also available in which a thermal curing-type coating-agent composition is used. Patent Literature No. 3 discloses a plastic article. In the plastic article, a first layer, which is made by curing a thermo-curing undercoating-agent composition being good in the weatherability, is disposed on a surface of a resinous substrate; and a second layer, which is made by curing a thermo-curing coating-agent composition being good in the wear resistance, is disposed on the first layer.